[Swan-dev] systemd watchdog support

[Tuomo Soini]

Ok. That feature was not fully designed.

Now libreswan depends on systemd and can't be build on systems without
systemd at all. systemd watchdog system must only be enabled if used
initsystem is systemd.

This is from build for el6:

/builddir/build/BUILD/libreswan-3.17/programs/pluto/pluto_sd.h:19:31:
error: systemd/sd-daemon.h: No such file or directory

And build fails.

-- 
Tuomo Soini <tis at foobar.fi>
Foobar Linux services
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